In recent years, a touch panel has come to be widely used as an input device in an electronic appliance, such as a mobile phone, a portable information terminal or the like. The touch panel is installed in a display device such as a liquid crystal display, an organic electroluminescence display or the like. As types of touch panels, touch panels of a resistive method, a capacitive method, and an optical method are known, for example. A user is allowed, according to any of these methods, to perform a desired operation by directly touching or sliding an operation object displayed on the display device. Therefore, an intuitive operating system is realized by the touch panel.
As technology relating to the touch panel, technology for performing key lock control of a mobile phone by using a touch switch is disclosed in Patent Literature 1 below, for example. Furthermore, technology for controlling on/off of key lock based on the order of operations of two touch switches is disclosed in the Literature. When using the technology described in the Literature, it becomes possible to prevent one from erroneously performing an on/off operation of key lock. In this manner, the convenience of a user can be improved by making good use of the touch switch and the touch panel.